1. Field of the Invention
The invention relates to slurry hydrocarbon synthesis. More particularly, the invention relates to a slurry hydrocarbon synthesis process in which the syngas is injected into the slurry with reduced catalyst attrition and deactivation using a gas distribution grid which comprises a plurality of throat and cone gas injectors extending through and arrayed across an otherwise gas and liquid impermeable tray.
2. Background of the Invention
Slurry hydrocarbon synthesis processes are known. In a slurry hydrocarbon synthesis (HCS) process, a synthesis gas (syngas) comprising a mixture of H.sub.2 and CO is bubbled up through a slurry in a reactor in which the slurry comprises solid catalyst particles and gas bubbles in a hydrocarbon slurry liquid at reaction conditions effective to convert the syngas to hydrocarbons, at least a portion of which are liquid at the reaction conditions, and with the slurry liquid comprising these liquid HCS products. The catalyst comprises a suitable Fischer-Tropsch type hydrocarbon synthesis catalyst. Reactors which contain such a three phase slurry are sometimes referred to as slurry "bubble columns", as is disclosed in U.S. Pat. No. 5,348,982. The catalyst particles are typically kept dispersed and suspended in the liquid by the lifting action of the syngas bubbling up through the slurry and by hydraulic means. The gas is bubbled up into the slurry by pipe grids, a plurality of pipes opening up into the slurry, or by means of a gas distribution grid or tray which the gas injectors comprise a porous or perforated plate, or a plurality of bubble caps, tuyres, risers or other gas injection means arrayed across and extending through an otherwise gas and liquid impervious, horizontal metal plate or tray at the bottom of the slurry and over the plenum space at the bottom of the reactor. Problems associated with the use of gas injectors include catalyst particle attrition, injector plugging, deactivation of catalyst settling on the grid and catalyst falling down through the injectors into the plenum space below. Attrition causes catalyst loss through fines production and this results in catalyst loss and plugging units downstream of the reactor. It would therefore be an improvement to the art to use gas injecting means which reduce or eliminate any of these problems.